Many of the telephone switching systems in service today operate in response to a stored program to provide telecommunication services to connected subscribers. This stored program contains data structures of fixed configuration and assigns memory in accordance with fixed principles. Some portion of the data describes the connections presently being made through the switching system. This latter data portion is dynamic in nature and is structured for ease of access and use by the stored program. From time to time, it is desirable to change substantially the controlling program so that new features and services can be provided. To provide the best possible service, stable connections through the switching system should not be disconnected when the program is changed. Thus, to convert from an old controlling program to a new controlling program, the new program must include a data base which defines the current connections being made through the switching system. The new program, however, may not be compatible with the old one. For example, it may be desirable to change the format of data structures to provide new information relating to a new service, or to delete information which is not needed by the new program. Accordingly, the new program cannot just copy the old data structures and be able to provide the telecommunication switching services.
One solution to this problem has been to generate special mapping programs which convert the old data structures and data layout to the form used by the new program. Although such mapping programs achieve the desired result, the construction of such programs is a large undertaking and provides many opportunities for error. Further, the mapping procedures of the new program must conform to the particular old program version being updated. Thus, many different mapping procedures have to be provided.
The present invention is a method and arrangement which allows the conversion from an old controlling program to a new controlling program while saving stable connections, but avoiding the problems of special data mapping procedures.